It was done to comply with rules on commenting and also allows them to spend up to £150,000 on referendum campaigning.

Scots firms Balhousie Care Group and Aquamarine Power said they were quitting as a result.

Scottish Enterprise and VisitScotland followed over the weekend and several other quangos are expected to follow after the Scottish Government said it was “inappropriate for ­government agencies to remain in membership”.

A spokesman for Glasgow University said yesterday: “In order to maintain our impartiality, we must resign our membership ­forthwith.”

An Aberdeen University spokesman said: “The university does not take an ­institutional position on the ­constitutional future of Scotland.”

"We believe that the role of a university is to inform the public debate through the contribution of its academic and research expertise."

A University of Edinburgh spokesman said: "While the University of Edinburgh hosts debate from all sides in the discussion around Scottish independence, we have a strictly neutral position on the issue as an institution.

"We have therefore withdrawn from membership of CBI Scotland while they are officially backing one side in that debate."

Glasgow Caledonian University are due to make a decision on their membership

Glasgow Caledonian University are also due to make a ­decision on whether they would quit CBI.

Dundee University will review membership later this week while Robert Gordon University in ­Aberdeen said they were not ­quitting but remained “strictly neutral” on independence.

A spokesman for Robert Gordon University said: "The purpose of the university's membership of the CBI is to assist in developing links with potential business partners. Such memberships are reviewed annually by the principal, in discussion with senior university officers.

"The university is strictly neutral in relation to the independence referendum, and does not approve of the CBI statement. However, we are not in the CBI in order to address Scottish independence."

CBI director general John ­Cridland said he was “very sad” to lose the universities as members.

He added: “All that changed is that for compliance reasons, we decided that we needed to register to be on the right side of ­regulations.

“We are not trying to influence the voter but we are a business organisation and on the business issues – jobs in Scotland, growth in Scotland, living standards in Scotland – we have a view.

“Scotland and the rest of the UK are stronger together on economic grounds as part of the Union.